1. Field of the Invention
The present invention relates to a method of filling a buffer chamber in a print head with bubbles and a corresponding printing apparatus.
2. Description of the Related Art
Known print heads are constructed so as to allow a plurality of ejection openings to be in communication, through a plurality of channels, with a common liquid chamber to which ink is supplied so that the ink in the common liquid chamber is selectively ejected through the plurality of ejection openings. With such a print head, a variation in pressure occurring when the ink is ejected is transmitted to the common liquid chamber, where the ink is then vibrated, causing the ink to be ejected unstably. A method of solving this problem is to fill a buffer chamber that is in communication with the common liquid chamber, with bubbles so that the buffer chamber serves to restrain the ink in the common liquid chamber from vibrating. When there are no bubbles in the buffer chamber, the heater provided correspondingly to the buffer chamber is driven to generate the bubbles in the ink in order to fill the buffer chamber therewith.
When the buffer chamber is to be filled with bubbles, control is provided so that the bubbles will not overflow the buffer chamber. If the bubbles overflow the buffer chamber, some of the bubbles become unstable and move along with the flow of the ink. These unstable bubbles must be sufficiently removed. If these bubbles invade any channel, the ink is ejected unstably. However, it is difficult to control the size of bubbles to be provided so as to prevent them from overflowing the buffer chamber. Thus, the danger of leakage is avoided by filling the buffer chamber with bubbles, the amount of which is substantially smaller than the capacity of the buffer chamber.
Further, the conventional buffer configuration does not allow bubbles to be sufficiently removed easily.